Alcohol elicits unique cardiovascular responses in the female population that are not only different from those seen in males but are also significantly influenced by the ovarian hormones, particularly estrogen. The objective of this proposal is to elucidate the molecular mechanisms implicated in the estrogen-dependent hemodynamic responses elicited by ethanol in female rats. Given the remarkable resemblance of the estrogen-dependent hemodynamic responses elicited by ethanol to the manifestations associated with mild endotoxicemia, we hypothesize that the NOS-NO signaling pathway plays a pivotal role in these responses. To test this hypothesis, we propose to conduct a series of integrative, signal transduction and gene expression studies under three aims. Aim 1 tests the hypothesis that activation of the vascular and/or cardiac nitric oxide synthases (NOS) mediates the estrogen-dependent hypotension and myocardial depression caused by acute alcohol in female rats. Since increased production of NO in the nucleus tractus solitarius (NTS) elicits hypotension, aim 2 studies will test the hypothesis that overproduction of NOS-derived NO in the NTS caused by additive or synergistic ethanol-estrogen interaction is implicated in the hypotensive and baroreflex depressant effects of acute ethanol in female rats. Aim 3 studies will identify the cellular mechanisms implicated in the chronic estrogen-dependent hypotensive and baroreflex depressant effects of ethanol in a model of surgical menopause. The proposal adopts a well-designed experimental approach that incorporates an established animal model, appropriate controls, and pharmacological interventions to: (i) establish a causal relationship between the up-regulation of NOS-derived NO in peripheral cells (myocyte and vascular smooth muscle) and neurons (NTS) and the estrogen-dependent cardiovascular effects of ethanol, and (ii) identify the molecular mechanisms implicated in the actions of ethanol, estrogen and their combination on NOS-NO signaling. The proposed research, whose primary focus is to probe the molecular mechanisms of estrogen-dependent hemodynamic effects of ethanol, addresses in a timely manner a significant biomedical problem and is expected to yield clinically relevant information.